With rapid advance of the technology of intellectualized machine tools, most modern five-axis machine tools or turn-mill machine tools are equipped and controlled by computers so as to perform multi-tasking machining processes automatically and thus to be competitive in the marketplace. The development and research of intellectualized machine tools are mostly focused upon how to prevent collision between various components of machine tools. Collision avoidance is especially important for high-end multi-axis machine tools. Workpieces to be machined by those high-end multi-axis machine tools are generally high-priced aviation and space parts, vehicle parts, or 3C parts, which are generally designed with many curved surfaces that are difficult to be machined and thus can often suffer heavy damage to workpieces or tools, depending on the intensity of the collision.
For collision avoidance, it is common to perform a pre-operation of machining simulation before any machining process is performed. The difficulty in this pre-operation is to obtain the accurate position of geometric models in the working space of virtual machine tools while workpieces, tools and fixtures usually have different configuration according to the machining process.
There are three methods that are currently available and used for overcoming the aforesaid problem, and one of which is a method of manual measurement. Operationally, the manual measurement method is performed by a worker who actually works to perform a measurement for obtaining the positions of workpieces and fixtures in the working space of a machine tool. The second method is a manual geometrical positioning method that is designed to move or rotate geometric models in a virtual machine tool for defining their relative positions. The last method is a method designed for enabling machining tools, workpieces and fixtures to be placed at their respectively scheduled positions that are stored in advance in machining plans.
However, the first method mentioned above can be very dangerous to the worker as he/she can easily hurt by the machine tool if not careful. The second method is short in its poor accuracy, and the third method is not preferred for its poor flexibility. Therefore, it is in need of a method for accurately detecting the positions of workpieces, tools, fixtures, and components of machine tools and then establishing geometric models in the working space of a virtual machine tool.